I don't think anyone was claiming the author was being intentionally deceiving, just that they're not very good at writing idiomatic Rust.
The first thing I'd suggest, as someone who's done their fair share of Rust compiler dev, is to stop using `Box` and `Ref` everywhere. Terms should not own their child terms; the idiomatic way to handle this is to use an arena and typed IDs, and pass a reference to the arena when you need access to the underlying data from the ID.